Pincerna vallis Chen & Wu, 2020

Chen, Zhe-Yu & Wu, Min, 2020, Two new cyclophoroid species from Hubei, China, with proposal of a new genus (Gastropoda, Caenogastropoda, Diplommatinidae and Alycaeidae), ZooKeys 935, pp. 37-46 : 37

Pincerna vallis Chen & Wu sp. nov. Figures 1 , 4A, B , 5A

Type material.

Holotype (HBUMM10017-spec. 1, fully mature animal), China, Hubei, Wufeng Tujiazu Autonomous County, Chaibuxi National Forest Park, 30.216N, 110.199E, 1220 m a.s.l., leg. Zhe-Yu Chen and Qiao-Zhen Hu, 27 June 2019 (Fig. 5A ). Paratype: 1 ex. (HBUMM 10017-spec. 2, an empty shell), same data as holotype.

Measurements. Shell width = 3.3 mm, shell height = 3.5 mm.

Diagnosis. R3 with some ribs. Ribs on R2 more intensive than those in P. costulosa .

Description. Shell conical ovoid, orangish when fresh, with 3¼-3½ convex whorls. Suture deep. Protoconch finely granulate, 1- 1¾ whorls. R1 ca 2½ whorls, with regularly spaced strong ribs. R2 very short (ca 0.5 mm), consisting of ca 15 lighter stripes (= breathing tunnels); constriction between R2 and R3 rather shallow. R3 slightly less than ¼ whorl, smooth near R2 side, with about 5 weak but distinct ribs near aperture. Aperture rounded, nearly vertical, not descending. Peristome expanded but not reflected, internally thickened, protruding; boundary between inner and outer peristomes visible. Umbilicus open, narrow. Operculum (Fig. 4A , arrowed) corneous, translucent, thin, concave.

Etymology. The name vallis (Latin: valley) refers to the type locality inside the Chaibuxi Grand Canyon.

Type locality. China, Hubei, Wufeng Tujiazu Autonomous County, Chaibuxi National Forest Park, 30.216N, 110.199E, 1220 m a.s.l.

Distribution. This species is known only from the type locality.

Remarks. Two Pincerna species have been recorded in adjacent areas, P. costulosa (Bavay & Dautzenberg, 1912) from Vietnam (Holotype: MNHN-IM-2000-31786, Tonkin, Phong Tho) (Fig. 4D ) and Yunnan, China (HBUMM10018, see below) (Fig. 4C ) and Pincerna maolanensis Luo, Zhang & Zhuo, 2009 from Guizhou. Pincerna vallis sp. nov. can be distinguished from P. maolanensis by its smaller and more fragile shell, relatively short R2 (ca 0.5 mm, whereas it is 0.83-1.00 mm in P. maolanensis ). Pincerna costulosa is most similar to the new species in size and shape. However, P. vallis sp. nov. has a more convex body whorl. Pincerna costulosa has a smooth/ribless R3 while the new species has some ribs near the aperture. In addition, the ribs of P. vallis sp. nov. on R2 are stronger than those in P. costulosa .

Vernacular name.

峡谷平沟螺

Figures

Figure 1. Map of sampling sites and type localities 1 type locality of Sinoarinia feii Chen, gen. et sp. nov. and Pincerna vallis Chen & Wu, sp. nov. 2 type locality of Sinoarinia maolanensis (Zhang, Chen & Zhuo, 2013) comb. nov. 3 type locality of Sinoarinia mirifica (Li, Zhuo & Luo, 2005) comb. nov. 4 type locality of Pincerna costulosa (Bavay & Dautzenberg, 1912) and Sinoarinia aesopus (Bavay & Dautzenberg, 1904) comb. nov., Vietnam 5 Sampling site of Pincerna costulosa in Yunnan.

Figure 4. A, B Pincerna vallis Chen & Wu, sp. nov. A HBUMM 10017 - spec. 1, holotype, red arrow shows the operculum B HBUMM 10017 - spec. 2, paratype C, D Pincerna costulosa (Bavay & Dautzenber g, 1912) C HBUMM 10018 D syntype, MNHN-IM- 2000 - 31786. Scale bar: 5 mm. Photos: Zhe-Yu Chen (A-C) and M. Caballer Gutierrez (D).

Figure 5. A Habitat of Pincerna vallis Chen & Wu, sp. nov. (HBUMM 10017 - spec. 1, holotype) B habitat of Sinoarinia feii Chen, gen. et sp. nov. Photos: Zhe-Yu Chen.